Far from being an isolated curiosity, the changing borders of Arunachal Pradesh are just one of many odd features present in Google’s mapping of China.

For example, In the map above, you might also notice that the river shown in the India and USA images is strangely absent from the Chinese map.

Below are the Chinese and U.S. versions zoomed in closer on the river. The dotted line is the border between China (above the line) and India (below the line).

A missing river and a missing road near the China-India border at Arunachal Pradesh

Indeed, the river is completely omitted from the Chinese map at any zoom level.

And for that matter, so is the road in the upper left corner of the image. It is visible below the border, but after the road crosses into China, it disappears.

In a sparsely populated region like Arunachal Pradesh, it may not be too surprising to find a few idiosyncrasies in Google Maps. But this next example makes it clear Google Maps is doing something strange when it comes to China.

Weirdness at the Hong Kong – China border

Next stop: the Hong Kong – China border

In no place is China’s peculiarity in Google Maps more apparent than at its border with Hong Kong.

China and Hong Kong are separated only by the narrow Shenzhen river. And with plenty of infrastructure and geographical features on both sides, the mapping differences are extremely apparent.

The images below are from the U.S. version of Google Maps, zoomed in on the Hong Kong – China border. Both images are the same, except that on the right, I have overlaid the road network from OpenStreetMap.

Below is an interactive version of Google Maps, zoomed in on the Hong Kong – China border. Tap the button to toggle the OSM road network on and off. See what it looks like when you switch to terrain mode.

What’s going on?

All of these strange features were implemented by Google Maps in order to comply with Chinese laws, laws designed to protect what China refers to as its “territorial integrity.”

Earlier this year, a spokesperson for the Chinese Foreign Ministry made this statement, giving some historical perspective.

“China suffered a long time of foreign aggression and humiliation in history… historical lessons teach us that we must build a national defense power, that is matched of national security needs, and economic development level. We will never allow any country to violate China’s sovereignty and territorial integrity”

As it relates to online maps, territorial integrity encompasses to two separate areas of Chinese concern:

National security

Territorial disputes

1. China considers precise mapping of its territory to be a national security risk

Chinese law prohibits the publication of geographic information about China. It considers such information to be State secrets, which could be used by its enemies to pinpoint military targets. Reportedly, the sentiment is a holdover from the Cold War.

“publishing, without authorization, significant geographic information and data concerning the territorial air, land and waters, as well as other sea areas under the jurisdiction of the People’s Republic of China.”

Since this law was introduced in 2002, China has pursued numerous cases of illegal mapping, with the accused parties ranging from foreign geology students to Coca Cola, who China investigated for illegal espionage in 2013 in relation to the GPS systems in its trucks.

Google Maps, Bing, and other online mapping services are able to publish maps in compliance with Chinese law because they conform to China’s so called GCJ-02 coordinate system, also referred to as Mars Coordinates.

GCJ-02 is based on the familiar WGS84 coordinate system, except that it is said to use an encryption algorithm to shift the coordinates by a few hundred meters from their true locations. As a result, GCJ-02 maps appear entirely self-consistent, but the actual coordinates of any given location are slightly offset from reality.

The GCJ-02 system (which Google Maps uses for China, but not for Hong Kong) explains the strangeness at the China – Hong Kong border. The two sides are mapped using entirely different coordinate systems.

The Hong Kong – China border is misaligned in Google Maps (left) but not in Map Quest (right)

However, Chinese laws have not stopped OpenStreetMap, MapQuest, and other websites from publishing precise maps of China online. The information provided by these and other readily available sources include coordinates that are accurate to within a few meters.

That being the case, it would seem China’s mapping laws are just a case of senseless paranoia. However, China’s fears are not without historical precedent.

In 1999, the U.S. bombed the Chinese embassy in Belgrade, later explaining it as an accident caused by an out of date map. And in 2010, Nicaragua and Costa Rica nearly went to war due to an inaccuracy in Google Maps.

A Google Maps error (left) that led to a Nicaraguan invasion of Costa Rica. Bing Maps (right) had the border correct. (Image courtesy of Fast Company)

2. China is also sensitive to what it considers inaccurate representations of its territory

As shown in the map of disputed territories I posted a few weeks ago, China is involved in disputes over 14 separate territories with 8 other countries, more than any other nation. And that doesn’t count Taiwan, Hong Kong, and Macau, all of which China considers under its sovereign control, despite each of them operating under separate political leadership and separate economic systems, including entirely different currencies.

Particularly sensitive at the moment is the territory claimed by China in the South China Sea. As shown in the map below, China’s self-declared maritime boundary (the dotted line) encircles nearly the entire sea, running right up against the coasts of Vietnam, Malaysia, and the Philippines, leaving each of them with only a thin buffer of sea territory.

South China Sea: China’s claimed maritime borders are shown by the dotted line

These three countries have pushed back, accusing Google of favoring China by labeling disputed islands under their Chinese names and/or explicitly identifying the islands as Chinese territory.

Earlier this year, Google Maps removed the Chinese name from one such island, Huangyan Island, and replaced it with its international name, Scarborough Shoal. Google made the change following an online petition that said its maps were unfairly strengthening China’s claims.

Currently, Google is named on an open petition to change the name “South China Sea” to “Southeast Asia Sea.” So far, 77,312 supporters have signed.

I'm an NYC-based entrepreneur (my newest project: Blueshift) and adjunct instructor at UPenn. I'm fascinated by data visualization and the ways that data is transforming our understanding of the world. I spend a lot of time with my face buried in Excel, and when I find something interesting I write about it here and also as a Guardian Cities and Huffington Post contributor.More about my background

Good posts. Would have expected the vector field to look a lot more complex. Seems pointless to make an “encrypted” coordinate system when the pattern is so clearly visible.

http://harrywood.co.uk harry_wood

Looking at the google maps screenshots I think some of these problems, like roads drawn over rivers, may not have anything to do with border disputes. It’s just a good old-fashion geo-data screw up. If you take data from a variety of sources, often river data often comes form a different organisation, and it’s easy enough to end up with a situation where the sources disagree dramatically.

In OpenStreetMap we see similar problems when people have done “imports” of data from a variety of sources. Often these are “official” and “authoritative” sources, and there’s an assumption that their accuracy will therefore be perfect. No such thing. With OpenStreetMap we have the advantage that people can spot the problems and edit the map to iron them out over time. That process sort of automatically happens, starting with the more noticeable problems affecting city maps.

Depending on the quantity of badly misaligned imported datasets, it can take a while though. This held back OpenStreetMap progress in the U.S. for quite a while actually (too many poor quality free government geo datasets imported), but these days there’s a fantastic U.S. map editing community getting on top of that problem. You can have fun with tools like http://maproulette.org finding and fixing data problems.

http://metrocosm.com Max Galka

Would not surprise me to see such inaccuracies but for the fact that they are different in the U.S. version. Can’t imagine why Google would use different sources for physical features in Google Maps China vs Google Maps USA. My guess is that Google removes / adds features from near the Chinese border to avoid glaring discontinuities. Though that is only a guess.

Of course, I would trust OpenStreetMap over Google Maps any day for the reasons you mention. Really an incredible undertaking, and an extremely valuable resource. Have been meaning to get involved myself. Maybe the link you sent would be a good place to start…

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